Angioscopy, defined as the endoscopic visualization of the inner surfaces of blood vessels, has evolved from early attempts at endoscopic examination of intracardiac anatomy to its use in peripheral vascular surgery. Its importance became apparent in 1977 when Towne and Bernhard published their experience with a rigid arthroscope and choledochoscope during 91 vascular reconstructions. They concluded that the use of angioscopy during vascular reconstruction permitted a more precise repair. The use of these bulky rigid endoscopes did not, however, gain wide acceptance. In the 1980's ‘ultrathin’ and very flexible angioscopes that are easy to use were developed. These have provided unique information, different from that attained using conventional angiography.

The basic components of the vascular endoscopy system are a fibreoptic imaging catheter containing illumination fibres, a high intensity light source, an irrigating system, and a video system with a camera and monitor.

Many larger imaging catheters or endoscopes (2.0–3.5 mm outer diameter) incorporate an irrigation channel into the catheter (Fig. 1) 372. Some also have a working lumen for passage of microinstruments, a steering guidewire, or a laser fibre. A deflectable tip is available with some models for steerability.

The narrow or ultrathin angioscopes (0.8–1.7 mm outer diameter) can be used for intraoperative or percutaneous diagnosis and treatment of peripheral vascular and coronary artery disease. They are not actively steerable and are best used with a disposable coaxial catheter for irrigation.

Pressurized heparin–saline (1 U/ml) is delivered through the irrigation channel or through another catheter to maintain a blood-free field for visual inspection. This solution can be delivered using a pressurized intravenous solution or through a commercially available foot controlled pump that regulates irrigation flow rates and can measure the volume of fluid administered. Excessive back bleeding can usually be controlled by increasing the irrigation fluid flow rate, but if this fails, control by external direct pressure, by an occluding balloon catheter, or by direct clamping of the artery may be necessary.

Although most angioscopes can be used with direct vision, indirect video imaging allows viewing by several people, video recording, and maintenance of a sterile field. Indirect video imaging employs a miniature camera mounted on to the angioscope catheter eyepiece. This provides a colour image 3 to 6 inches (8–15 cm) in diameter on a video monitor. A xenon light source of at least 300 W is generally used to provide illumination at the angioscope tip.

There are several important differences between arteriography and angioscopy. Conventional arteriography only provides a two-dimensional image of the arterial tree, which can be misleading without biplanar views. Although angiography does not provide information about the aetiology of the narrowed or obstructed segment, angioscopy can be used to differentiate between thrombotic and atheromatous elements of these lesions. Angioscopy is also an alternative to intraoperative arteriography for assessment of a graft and its anastomotic patency, but it cannot provide information about the distal run-off, as can arteriography.

Angioscopic criteria for the diagnosis of abnormal blood vessels include an oval or slit shaped cross-section, eccentric or concentric stenoses, inhomogeneous colour of the vessel wall, thrombotic deposits on the walls, ulceration, and slow restitution of blood flow after flushing of the lumen.

Findings at the time of the endoscopy may change the operative management: in one series this occurred in 14 per cent of patients examined. Revisions were necessary for misplaced sutures, redundant graft material, or atheromatous flaps not incorporated into the anastomosis causing partial obstruction of the lumen.

Angioscopy is becoming a valuable asset in the preparation of in- situ bypass grafts. Angioscopically directed localization and incision of the greater saphenous vein valves helps to ensure complete disruption of the valve cusps for an in-situ bypass (Fig. 2) 373. The angioscope can also be used to identify venous side branches for ligation and to assess distal anastomotic patency. Venous injury by misplacement of the valvulotome into a side branch of a vein can be prevented by direct visualization. Angioscopy can also identify pathologically sclerotic vein segments and other venous abnormalities that could result in early graft failure.

Thromboembolectomy with the balloon catheter is generally performed as a blind procedure. As a result, the completeness of the thromboembolectomy is unknown, and intraoperative angiography is limited to the detection of a total occlusion or major thrombus. The addition of angioscopy to the procedure has several advantages over conventional thromboembolectomy including accurate detection, localization, and retrieval of the thrombus or embolus (Fig. 3) 374. Angioscopy also facilitates the cannulation of bifurcating tributaries, such as the tibial vessels, with the balloon catheter. It is difficult to know the clinical impact of these procedures or the clinical significance of retained thrombus during thrombectomy since the ‘blind’ procedure has a relatively high success rate.

Angioscopically assisted intraluminal instrumentation has added a new dimension to the management of peripheral vascular disease. Angioscopes have been used to direct atherectomy and laser assisted angioplasty. Angioscopy performed percutaneously with special catheters can also be used to assist in and to monitor the results of thrombolytic therapy or standard balloon angioplasty.

Despite the increasing popularity and use of angioscopy, few complications have been reported. The potential for injury to the vessel wall gives rise to most concern. After simulated angioscopic insertion into canine veins in vivo, minor intimal abnormalities are seen acutely; these are completely repaired within 2 weeks and veins which suffer subtotal loss of endothelium are replaced in 3 to 4 weeks.

Another complication secondary to any instrumentation of a blood vessel is arterial spasm. This problem may affect early patency and could increase the likelihood of vessel injury or perforation. Pretreatment with papaverine (0.5 mg/ml), especially useful in vein grafts, can be used to obviate the spasm.

Volume overload is a potential hazard which can arise if large volumes of irrigation fluid are used to keep a clear visual field. Fluid balances must be carefully monitored during angioscopy to avoid the development of pulmonary oedema, especially when a large irrigation catheter is used or when intra-arterial catheterization is needed, because larger volumes of irrigation may be required.

Magnification of intraluminal defects by the angioscopic optical system presents the vascular surgeon with the problem of interpreting their relevance. Towne and Bernhard reported a 29 per cent incidence of possibly important lesions identified by angioscopy. This incidence does not however, correlate with the early failure rate of vascular grafts. Clearly there is a definite learning curve to assess which lesions require correction or reconstruction and which may be ignored.

Angioscopy is becoming an important part of the vascular surgeons' armamentarium for both the diagnosis and treatment of peripheral vascular disease. By allowing the immediate detection and correction of technical errors and intravascular pathology its use may improve graft patency. For specific indications, angioscopy has also been shown to be an effective alternative to intraoperative angiography, but it is unlikely that angioscopy will replace angiography. As technological advancements improve angioscope systems and their use and indications widen, vascular surgeons will need to learn how best to use and interpret their findings. By carrying out routine angioscopy during arterial surgery, the vascular surgeon will be able rapidly to assess endovascular anatomy and thus potentially reduce graft failure rates and improve limb salvage.

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